Portail HAL de l'Université du Littoral Côte d'Opale
Not a member yet
11255 research outputs found
Sort by
Joint simulation of urban vehicle traffic and relay-empowered 5G communications at city scale
No full textInternational audienceThe fifth and beyond generations of communications (B5G/6G) aim to support massive connected objects and mission-critical applications. In the context of disaster management, the vehicles coordinating rescue operations in each area can also serve as local communication relays for the other participants. The evaluation of such applications at a city scale requires accurate modelling of both urban mobility and vehicular communications. Most works propose either analytical models providing a big picture of the performance expected in large-scale deployments, or real-world testing at a lower scale showing performance for concrete but limited scenarios. This paper proposes a simulation approach to the evaluation of 5G relay-empowered communications, which uses an event-based urban traffic modelling in order to accelerate large-scale simulations. It also uses propagation models designed from real-world measurements performed on mobile operators’ 5G infrastructure, which allows to envision the 5G communication performance that could be expected for applications such as cooperative localization and extended perception between the participating vehicles. The evaluations over a relay-empowered 5G network including one base station (gNB), 180 relays, and up to 350 vehicles in an urban city show that the relays improve downlink communications speed and end-to-end delay, while the gNB provides higher speeds in uplink communications overall. These evaluation results draw the performance expected from existing 5G deployments, and offer insight for communication management policy regarding the applications involved in rescue operations
From Accident to Improvement: A Case Study of Nitric Acid Splashing into Eyes During a Teaching Lab
No full textInternational audienceDuring a laboratory session involving the acidic digestion of a soil sample for flame atomic absorption spectroscopy, a student sustained a near-miss eye injury due to a concentrated nitric acid splash following the detachment of the syringe and filter. The incident occurred during filtration of the digested solution containing concentrated nitric acid through a 0.45 μm syringe filter using a 10 mL Luer slip syringe. This report presents a detailed analysis of the incident using cause-tree methodology to identify contributing factors. The root cause analysis revealed a combination of procedural gaps (lack of specified syringe size and filtration of concentrated solution), inadequate technique (excessive pressure on the plunger and improper positioning at the fume hood), and suboptimal use of protective equipment. Based on these findings, staff implemented corrective actions, including protocol modifications (dilution of the acid prior to filtration, specification of a 1 mL syringe), enhanced training on proper filtration techniques and fume hood use, and procurement of improved safety goggles. This case study highlights the importance of well-designed and detailed procedures, proper training, and appropriate use of protective equipment in preventing laboratory accident
: Isis, from Antiquity to the Renaissance
No full textInternational audienceDue to her Egyptian origin, Isis could have remained confined tothe Nile Valley. However, the goddess and her companions, Osiris, thenSarapis, Anubis, Harpocrates experienced a revival and a big successaround the Mediterranean during the Hellenistic Period, then underthe Roman Empire. These deities, even modified in their look andfunctions, create reactions from Greek and Latin authors who caricaturetheir specificities. At the turn of the Middle Ages and the Renaissance,we are rediscovering these same authors and their vision.Divinité profondément égyptienne, Isis aurait pu rester cantonnéeà la vallée du Nil. Pourtant, la déesse et ses compagnons, Osiris puisSarapis, Anubis, Harpocrate connaissent un renouveau et un succèsdans le bassin méditerranéen à l’époque hellénistique puis sous l’Empireromain. Ces divinités, même transformées dans leur apparence etleurs fonctions, suscitent des réactions des auteurs grecs et latins, quicaricaturent leurs spécificités. Or, ce sont ces mêmes auteurs et leur visionque l’on redécouvre à la charnière du Moyen Âge et de la Renaissance
Interval Particle Filter for LiDAR-Based Object Tracking
No full textInternational audienceThis paper presents an Interval Particle Filter (IPF) for robust target tracking in autonomous systems, based primarily on LiDAR measurements. The IPF framework combines probabilistic sampling with interval analysis to provide guaranteed error bounds, improving robustness in uncertain environments. It maintains a set of weighted interval particles that recursively estimate the target state through prediction, correction, and refinement steps. The main contributions are: (i) an interval-based measurement update that contracts particle state bounds using LiDAR observations, and (ii) a weight update mechanism based on contraction ratios. Experimental results on an Autonomous Surface Vehicle (ASV) tracking task demonstrate the IPF robustness to both measurement and process uncertainties compared to conventional particle filtering techniques
Science-fiction et management de l’innovation
No full textInternational audienceScience fiction is an imaginary that plays a crucial role in economic processes. Innovation management can use it in its prototyping and foresight work. Design fiction and science fiction prototyping methods thus use science fiction to stimulate the creativity of organizational members. Science fiction therefore appears both as a critical imaginary of the technostructure, but also, increasingly often, as a system of representations of the future useful to capitalism to stimulate technoscientific innovation. Organizations therefore have an interest in relying on science fiction to imagine their future. The texts gathered in this issue deal both with the way in which organizations use science fiction to innovate and foresight, but also with the representations of organizations in certain works.La science-fiction est un imaginaire jouant un rôle crucial dans les processus économiques. Le management de l’innovation peut l’utiliser dans ses travaux de prototypage et de prospective. Les méthodes du design fiction et du science fiction prototyping l’utilisent ainsi pour stimuler la créativité des membres des organisations. La science-fiction apparait donc à la fois comme un imaginaire critique de la technostructure, mais aussi, de plus en plus souvent comme un système de représentations du futur utile au capitalisme pour stimuler l’innovation technoscientifique. Les organisations ont donc intérêt à s’appuyer sur la science-fiction pour imaginer leur avenir. Les textes regroupés dans ce numéro traitent à la fois de la manière dont les organisations utilisent la science-fiction pour innover et faire de la prospective, mais aussi des représentations des organisations dans certaines œuvres
Toward more robust net primary production projections in the North Atlantic Ocean
No full textInternational audiencePhytoplankton plays a crucial role in both climate regulation and marine biodiversity, yet it faces escalating threats due to climate change. Understanding future changes in phytoplankton biomass and productivity under climate change requires the utilization of Earth system models capable of resolving marine biogeochemistry. These models often differ significantly from one another, and most studies typically use the average response across an ensemble of models as the most reliable projection. However, in the North Atlantic, this straightforward method falls short of providing robust projections of phytoplankton net primary production (NPP) over the 21st century. A new inter-comparison approach was therefore developed and applied to eight models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) exhibiting substantial divergence in their NPP projections in the North Atlantic. The basin was first divided into three bioregions tailored to the characteristics of each model using a novel method based on a clustering procedure. The mechanisms controlling NPP projections were then identified in each model and in each bioregion, revealing two mechanisms responsible for a large part of model divergence: diazotrophy in the subtropical region and the presence of an ammonium pool in the subpolar region. This allowed for an informed selection of models in each region based on the way they represent these two mechanisms, resulting in reduced projection uncertainty, enhanced total NPP decrease in the subtropical region, and a strengthened increase in small phytoplankton NPP in the subpolar North Atlantic. These model selections enhanced the decreases in carbon export and phytoplankton biomass but had no impact on zooplankton biomass. This innovative approach has strong synergies with other widely used inter-comparison techniques, such as emergent constraints, and their combination would provide valuable insights into the future trajectory of the Earth's climate syste
Modélisation et analyse technico-économique d'un réseau de transport d'hydrogène pour la France.
No full textThis article belongs to the Special Issue Revolutionizing the Automotive Landscape: Fuel Cell Applications Powering the FutureInternational audienceThis work aims to study the technical and economical feasibility of a new hydrogen transport network by 2035 in France. The goal is to furnish charging stations for fuel cell electrical vehicles with hydrogen produced by electrolysis of water using low-carbon energy. Contrary to previous research works on hydrogen transport for road transport, we assume a more realistic assumption of the demand side: we assume that only drivers driving more than 20,000 km per year will switch to fuel cell electrical vehicles. This corresponds to a total demand of 100 TWh of electricity for the production of hydrogen by electrolysis. To meet this demand, we primarily use surplus electricity production from wind power. This surplus will satisfy approximately 10% of the demand. We assume that the rest of the demand will be produced using surplus from nuclear power plants disseminated in regions. We also assume a decentralized production, namely, that 100 MW electrolyzers will be placed near electricity production plants. Using an optimization model, we define the hydrogen transport network by considering decentralized production. Then we compare it with more centralized production. Our main conclusion is that decentralized production makes it possible to significantly reduce distribution costs, particularly due to significantly shorter transport distances.Ce travail vise à étudier la faisabilité technique et économique d’un nouveau réseau de transport d’hydrogène d’ici 2035 en France. L’objectif est d’équiper les bornes de recharge des véhicules électriques à pile à combustible avec de l’hydrogène produit par électrolyse de l’eau à partir d’une énergie bas carbone. Contrairement aux travaux de recherche antérieurs sur le transport de l'hydrogène pour le transport routier, nous supposons une hypothèse plus réaliste du côté de la demande : nous supposons que seuls les conducteurs parcourant plus de 20 000 km par an passeront aux véhicules électriques à pile à combustible. Cela correspond à une demande totale de 100 TWh d’électricité pour la production d’hydrogène par électrolyse. Pour répondre à cette demande, nous utilisons principalement la production excédentaire d’électricité issue de l’énergie éolienne. Ce surplus satisfera environ 10% de la demande. Nous supposons que le reste de la demande sera produit à partir des surplus des centrales nucléaires disséminés dans les régions. Nous supposons également une production décentralisée, à savoir que des électrolyseurs de 100 MW seront placés à proximité des centrales de production d'électricité. À l’aide d’un modèle d’optimisation, nous définissons le réseau de transport d’hydrogène en considérant une production décentralisée. Ensuite, nous le comparons à une production plus centralisée. Notre principale conclusion est que la production décentralisée permet de réduire significativement les coûts de distribution, notamment grâce à des distances de transport nettement plus courtes
A Comprehensive Survey of Benchmarks for Improvement of Software's Non-Functional Properties
No full textInternational audienceDespite recent increase in research on improvement of non-functional properties of software, such as energy usage or program size, there is a lack of standard benchmarks for such work. This absence hinders progress in the field, and raises questions about the representativeness of current benchmarks of real-world software. To address these issues and facilitate further research on improvement of non-functional properties of software, we conducted a comprehensive survey on the benchmarks used in the field thus far. We searched five major online repositories of research work, collecting 5499 publications (4066 unique), and systematically identified relevant papers to construct a rich and diverse corpus of 425 relevant studies. We find that execution time is the most frequently improved property in research work (63%), while multi-objective improvement is rarely considered (7%). Static approaches for improvement of non-functional software properties are prevalent (51%), with exploratory approaches (18% evolutionary and 15% non-evolutionary) increasingly popular in the last 10 years. Only 39% of the 425 papers describe work that uses benchmark suites, rather than single software, of those SPEC is most popular (63 papers). We also provide recommendations for future work, noting, for instance, lack of benchmarks for non-functional improvement that covers Python, JavaScript, or mobile devices. All the details regarding the 425 identified papers are available on our dedicated webpage: https://bloa.github.io/nfunc_survey